Titan's topography, strange.... |
Titan's topography, strange.... |
Apr 12 2009, 12:44 PM
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Senior Member Group: Moderator Posts: 2785 Joined: 10-November 06 From: Pasadena, CA Member No.: 1345 |
Recent article in Science by Zebker et al.:
Zebker et al. Science in press, "Size and Shape of Saturn's Moon Titan". doi: 10.1126/science.1168905 (published online April 2, 2009) Link to abstract (pay-for article): http://www.sciencemag.org/cgi/content/abstract/1168905 Article on spaceref discusses this paper: http://www.spaceref.com/news/viewpr.html?pid=27912 Figure 3 from the Science article is a global elevation map relative to barycenter. Key points of article:
"Xanadu seems to be systematically lower than other parts of the equatorial belt, and not uplifted like most mountainous areas on Earth." (quote from Fig. 3 caption in article) -Mike -------------------- Some higher resolution images available at my photostream: http://www.flickr.com/photos/31678681@N07/
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Apr 15 2009, 05:10 PM
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#2
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Senior Member Group: Moderator Posts: 2785 Joined: 10-November 06 From: Pasadena, CA Member No.: 1345 |
If I understand this correctly, the dunes line up along the vector addition product of the alternate wind vectors.
So 50% winds blowing from the NW + 50% winds blowing from the SW will give an EW dune (with the mobile dune particles kinda marching to the E). The change in wind direction could be daily, or seasonal. [http://www.tec.army.mil/research/products/...et/lslinear.htm] (Another clue to average wind direction vector is dune bifurcation, in case of Y-junctions, the "stem" of the Y is downwind.) The key is that to make a stable linear dune, the difference between the two alternate vectors has to be pretty large. Otherwise, the linear dune will decay into a barchan-type dune. Check out: http://www.comphys.ethz.ch/hans/p/457.pdf Extending this to the linear dune direction change to the SSE vector in E Shangri-La/W Xanadu, BOTH alternate wind vectors need to be shifted. So the evidenced wind regime near the margin should be (assuming a 90 degree alternate vector (theta-w) difference) WNW alternating with NNE winds. -------------------- Some higher resolution images available at my photostream: http://www.flickr.com/photos/31678681@N07/
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